Henna (hina) is a flowering plant with the botanical name lawsonia inermis. It contains a red-orange pigment, lawsone, also known as hennotannic acid. This pigment is released by crushing the henna leaves in an acidic medium. The lawsome molecules will then have the ability to stain, and when applied to the skin they migrate to the outermost layer or cuticle, and stain them.

Commercially available henna powder is made by drying the henna leaves and milling them to a powder, which is then sifted.

To use henna, the powder is mixed with water and/or lemonjuice, to form a smooth paste. The henna mix must rest for 6 to 12 hours so that the leaf cellulose is dissolved, making the lawsone available to stain the skin. The longer the paste is left on the skin or hair, the more the lawsone will migrate, thus making the staining darker.

"Henna has a wide spectrum of antimicrobial activity including antibacterial, antiviral, antimycotic and antiparasitic activities. With the ever increasing resistant strains of microorganisms to the already available and synthesised antibiotics, the naturally available Laswonia inermis (henna) could be a potential alternative."

A study carried out in the UAE found that the henna plant had the medicinal properties of reducing inflammations, and being a pain reliever. [2]

A research paper published in 2005 found that henna leaves inhibit the growth of certain microorganisms, and could therefore be used to treat burn wound infections. [3]

"The henna leaves extracts were able to inhibit the growth pattern of A. niger and F. oxysporum. Streptococcus sp. and S. aureus were also inhibited by the extracts. Inhibition of the microorganisms' growth suggests that henna may be valuable in the management of burnt wound infections."

This modern research provides evidence for some of the health benefits that Ibn al-Qayyim mentioned about henna over 600 years ago.

Tips on Using Henna

Fresh henna powder should be a vibrant and deep green, whilst old henna may appear slightly brown.

Commercial henna pastes may contain additional ingredients to enhance their staining-power, and some are unsafe so always check the label. Black henna is especially harmful as it may contain para-phenylenediamine (PPD), a chemical that can cause itching, blistering and scarring.

Adding essential oils with high levels of monoterpenes or terps such as tea tree, eucalyptus, cajeput, or lavender to the henna paste will improve its staining ability.